Bayern Munich have rubbished rumours they had already agreed terms with Borussia Dortmund striker Robert Lewandowski.

Bayern this week provoked controversy over the signing of Germany international Mario Gotze from Dortmund. BVB first said no one at Bayern had been in touch over the transfer, and coach Jurgen Klopp then expressed his frustration that the news had leaked in the build-up to his side's Champions League semi-final with Real Madrid.

The relationship between the two clubs threatened to deteriorate further as reports in several newspapers suggested Bayern had made a €25 million for Lewandowski through a middleman, but Dortmund general manager Michael Zorc dismissed that speculation.

Klopp had earlier expressed confidence that Lewandowski, who has just one year remaining on his contract, would still be at the club next season.

However, Bild has claimed Dortmund failed in an attempt to hold talks with the Poland international over a new deal, with the striker said to have already agreed terms with Bayern. One contract, the paper said, would come into force if he made the move this summer, while the other would be valid from 2014, when his Dortmund deal expires.

Bayern issued a press release rejecting that claim on Friday morning, stating: "Contrary to the reports, FC Bayern has no contract with Robert Lewandowski."

Even so, there are growing concerns over Bayern's approach to the transfer market, with the club attracting heavy criticism for the manner in which they have poached talent from other Bundesliga sides.

Mainz general manager Christian Heidel, speaking at a Frankfurter Rundschau podium discussion, said the way Bayern currently handled transfers was "unworthy of a German champion", citing the transfer of centre-back Jan Kirchhoff, who in January signed a pre-contract at the Allianz Arena.

"At some point, we heard that a medical had been done at Bayern," Heidel said. "As of today, we are still waiting for a short phone call to tell us that our player agreed the contract."

Eintracht Frankfurt general manager Bruno Hubner added he could "only confirm Heidel's impressions", with his club set to lose holding midfielder Sebastian Rode to Bayern.

Hubner added: "Other interested parties opted out, as they were under the impression Rode's future was decided."

According to German Football League regulations, Bayern had been obliged to contact Frankfurt for permission to negotiate as Rode's contract is not due to expire until the end of next season. The date of the transfer has not been confirmed.